Selective ortho substitution of phenol cpds. - by gas phase reaction with methanol or di:methyl ether over mixed oxide catalyst

摘要

Prodn. of ortho-substd. phenols (I) comprises reacting a phenol (II), opt. mono- or di-alkyl substd. but with at least one free ortho position, in the gas phase with methanol and- or dimethyl ether at mole ratio 1:0.1-10. Reaction is at 270-390(300-380) deg.C with dwell time 0.05-10(1-3.5)sec. over a mixed oxide catalyst (A). (A) comprises (a) Fe oxide; (b) Cr oxide; (c) Si oxide; and (d) at least one alkaline earth, La and Mn oxide; or (a) Fe oxide; (b) Cr oxide; (c) at least one of Ge, Ti, Zr, Sh and Pb oxides, and (d) at least one alkali and-or alkaline earth metal, La and Mn oxides, there being 0.1-10 moles each of (b), (c) and (d) per 100 moles (a). 2,6-Dimethylphenol is an intermediate for poly(phenylene oxide) and 2,4,6-dimethylphenol is used in prodn. of Vitamin E. Selectivity for ortho substitution is 98-99% and even after 2000 hr. operation there is no significant decrease. Methanol consumption is substantially lower than in known processes.